PHILOSOPHY OF RELIGION: A contemporary introduction

FAITH AND REASON 345

3 Explanations in physics use no concepts and no laws save those of

logic and physics.

4 All explanation is explanation in physics. (from 1 and 2)

5 All explanations use no concepts and no laws save those of logic and

physics. (from 3 and 4)

Here, a reminder about explanations is relevant. Explanations have two parts.
One part is an explicandum or to-be-explained – an explainee, if you like –
that tells you what the explanation is an explanation of. This must be described
in terms that are accessible to the other part of the explanation. The other part
is an explicans or explainer that tells you what is the reason for the explainee;
this by itself is often called “the explanation.” A genuine explainee is one that
can be related to a genuine explainer. If, as premise 5 says, all explanations are
explanations in physics, then all explainers can be described in all ways
relevant to explanation only by the concepts of physics. Then all explainees
must be related by the laws of physics to the explainers. Then for all purposes
relevant to explanation the explainees must be described only by the concepts
of physics.

6 For all purposes relevant to explanation, one needs nothing other than

physical concepts and laws to explain or describe anything. (from 5)

7 Any (non-ultimate) property that a thing has is a property for which

there is an explanation.

An ultimate property, defined in terms of the present argument, will be any
property, defined in purely physical terms, that physical theory takes things to
have but cannot explain their having.

8 One needs nothing to describe or explain any (non-ultimate) property
that anything has except the laws and concepts of physics. (from 6, 7)
9 If one needs nothing other than physical concepts and laws to explain or
describe any (non-ultimate) property, and all explanations are
explanations in physics, then all of our knowledge is physical knowledge.
10 All of our knowledge is physical knowledge (knowledge in physics, fully
expressible in terms of the concepts of physics). (from 8, 9)

Here, we reach the conclusion scientism requires. The problem is that the
argument naturally continues as follows:

11 Reference only to physical descriptions and explanation of things will
not justify us in thinking that something is an explanation, or in
thinking that all of our knowledge is physical knowledge (knowledge
in physics, fully expressible in terms of the concepts of physics).